マウス２細胞卵子における3H-メチオニンの取込みに及ぼすEDTAの影響

To investigate the effect of EDTA on the in vitro development of mouse embryos from 1-cell to blastocyst, the embryos were cultured in M 16 and M 16 plus EDTA. The incorporation of［3H］methionine was also compared. A significant increase in the number of four-cell embryos (87.5 %) and blastocysts (71.9 %) was observed when embryos were cultured in M16 with EDTA compared to basic M16 medium (23.5 % and 2.9 %, respectively). When considering the results of first two incorporation experiments together, the lowest incorporation of［3H］methionine was observed at 45 h after hCG injection in both medium. So, we may explain that cell block in the in vitro embryo development occurred within a relatively narrow range of time, during 40-45 h after hCG injection. On the other hand the incorporation of［3H］methionine differed between ICR and C57B/6 strains and indicated that in blocking strain mice care must be taken to ensure that embryos at the 2-cell stage are recovered from the oviducts late enough in the second cell cycle for their normal development